Cinematographic sound-track printing



Jan. 31, 1950 w, E, POHL v 2,495,821

CINEMATOGRAPHIC SOUND-TRACK PRINTING Filed Sept. 29, 1945 Nk@ il C wj QU r if, jf

Patented Jan. 3l, 1950 CINEMATGRPHIC SOUND-TRACK PRINTING Wadsworth E. Pohl, Los Angeles, Calif., assigner to Technicolorv Motion Picture Corporation, Hollywood, Calif., a corporation of Maine Application' September 29, 1945, Serial No. 619,315

3 Claims.

In the art of recording sound on film various recording methods have been proposed. The customary way is to sensitize the'sound-track zone with silver salts, print the sound-track with light, and ythen develop the sound-track in silver. It has alsobeen proposed to print the sound-track by imbibition. A silver track has the disadvantage of graininess, resulting in ground-noise. Imbibif tion tracks have not been satisfactory because the available dyes do not have sufficient absorptivity for light of the spectral ranges to which reproducing photo-cells are sensitive.

.In the art of printing both pictures and soundtrack from a matrix on a dye-absorptive film, it has been proposed to sensitize the sound-track zone of the dye-absorptive film with ferrie iron salts and, while printing the pictures by imbibition, printing the sound-track with light to convert the ferric salts into ferrous salts, developing the i-llm With a soluble iron cyanide developer to form an opaque insoluble iron cyanide, and Washing the lm to remove the undeveloped iron salts. In this procedure both the picture areas and the sound-track zone of the matrix are dyed with a dye suitable for imbibition printing. In printing the pictures by imbibition the dye in the sound-track zone of the matrix also transfers to the dye-absorptive blank. However the transfer of dye in the sound-track zone is incidental because the specially sensitized sound-track Zone of the blank is printed with light modulated by the dye in the sound-track zone, before the sound-track dye has transferred, after vrit has transferred or while it is partly in the matrix and partly in the blank.

While this method of printing pictures by imbibition and the sound-track by light on a specially sensitized zone of the dye-absorptive blank has many advantages over other printingmethods, it has one disadvantage. WhileA the remove the undeveloped iron salts.

2 erally superior to sound-tracks as heretofore produced.

In the preferred application of the present invention the sound-track is formed in a water absorptive lm by sensitizing the sound-track zone with ferric iron salts, printing the soundtrack with light to convert the ferrie salts into ferrous salts, developing the lm with a soluble iron cyanide developer to form an opaque insoluble iron cyanide, and Washing the film to While the entire film may be thus sensitized the ferric salts are preferably confined to the sound-track zone to avoid any danger of contaminating the picture areas. By using a ferricyanide developer the converted ferrous salts are developed, whereas by using a ferrocyanide the unconverted ferric salts are developed. Thus when using a ferricyanide developer the sound-track should be printed from a negative and when using a ferrocyanide developer the sound-track should be printed from a positive. The ferricyanide developer may be incorporated in the iilm along with the light-sensitive ferrie salts or it may be applied after exposure as is customary with developers. When the ferricyanide is incorporated in the lm, development begins as soon as the exposed lm is wetted. However the ferrocyanide developer can only be applied after exposure; if incorporated in the film before exposure it would immediately react with the ferric salts uniformly throughout the entire width of the sound-track zone.

While various iron cyanides may be used as developers sodium or potassium ferricyanide is preferable, and the most satisfactory sensitizing solution thus far obtained is the following:

films are held together for imbibition printing disadvantages, which is substantially free from.`V

graininess, which has adequate absorptivity vfor light to which photo-cells are sensitive, which can be produced in an ordinary imbibition process with facility and without adding substantially either to the cost of the process or the time of carrying out the process, which is uniform throughout successive printings with the same matrix, which requires less dye and which is gn- Ferrie ammonium oxalate (pearls) grams- 2K7 For ferrocyanide development the sensitizing solution may comprise:

Ferrie ammonium oxalate (pearls) grams-- 27 Ferrie oxalate (pearls) do 4.5 Hydrochloric acid, C. P mls-- 10 Water mls 55 For developing a lm sensitized in this way the` bath may comprise:

Potassium ferrocyanide grams Water mls The invention involves a method of printing pictures by imbibition, from a dyed matrix having both pictures and a sound-track, on a Water ab- 3 sorptive film having its sound track zone sensitized with ferrie iron salts, the method comprising continuously conducting the film and matrix along predetermined paths with the film and matrix in face-to-face Contact along a common portion of the paths to permit dye to'be imbibed by the film from the matrix and, in the aforesaid common portion, printing the sound-track in the aforesaid film with light passing through the matrix to convert the ferric salts into ferrous salts and, farther along the path of the film, developing the film with a soluble iron cyanide developer to produce a sound-track in the form of a light-absorptive, insoluble iron cyanide, and finally washing the film to remove the unexposed iron salts. While the sound-track of the matrix may be in any suitable form,V it is preferably in the form of a dyed relief like the pictures, in which case both pictures and sound-track may be dyed in the same operation in advance of the location where the sound-track is printed as aforesaid. In imbibition printing it is particularly advantageous to incorporate a ferricyanide developer in the film, along with the ferric iron salts, because the imbibition pr cess normally involves the use of a water bath and thus the sound-track may be developed while the lm is traveling through this water bath without the necessity of adding a separate developing step.

According to the present invention the matrix, after it is dyed and before it reaches the blank film, is treated in its sound-track zone to prevent dye transfer from matrix to blank in that zone, whereby the sound-track zone ofthe matrix need be dyed only once and the dye in this zone need not be replenished for successive printiugs. Not only does this require less dye but it avoids the aforesaid difficulty resulting from the migration of the iron salts from the blank to the matrix. Inasmuch as the sound-track zone of the matrix need not be re-dyed after the rst printing, the aforesaid hardening of the sound-track Zone of the matrix by the iron salts from the blank is immaterial. While there are various ways of preventing the dye in the sound-track zone of the matrix from transferring to the blank film while the dye in the picture areas is being transferred, preferably the dye in the sound-track Zone is mordanted by application of a suitable mordant in the sound-track zone. When printing pictures with an acid dye, as is customary in imbibition printing, the mordant preferably comprises a basic dye. Suitable acid dyes are metanil yellow (C. I. 138) and chrysophenine G (C. I. 365) and suitable basic dyes are chrysoidine G (C. I. 20)Y and methylene green B (C. I. 924).

In another aspect the present invention involves a novel matrix which contains in its picture areas dye which is free to transferto the blank film in imbibition printing and also containing in its sound-track zone dye which is mordanted so as not to transfer when the pictures are printed. In still another aspect the invention involves a printed film having imbibition pictures which comprise acid dye and a sound-track in the form of'a light-absorptive, insoluble, iron cyanide, the sound-track zone being substantially free from the aforesaid acid dye.

For the purpose of illustration typical apparatus for practicing the invention are shown in the accompanying drawings in which Fig. 1 is a diagrammatic view of one embodiment;

Fig. 2 is a plan view of a suitable device for 4 applying the sensitizing solution to the soundtrack zone of the blank and the mordanting solution to the sound-track zone of the matrix; Fig. 3 is a side elevation of the device; and 5 Figs. 4 and 5 are views on lines 4-4 and 5 5 respectively of Fig. 1.

The apparatus shown in Fig. 1 comprises an endless pinbelt I traveling in an orbital path over drums 2 and 3, the belt having teeth adapted to fit into the sprocket holes of films. Thuswhen two lms are applied to the belt in superposed relationship they are held in iixed position in relation to each other and to the belt while traveling with the belt along the aforesaid orbital path. As shown in Fig. 1 the lm F to be printed is fed to the belt between two pressure rollers 4 which seat the film on the belt, and the matrix M is fed to the belt between pressure rollers 6 which seat the matrix on the film F. The iilm F is fed from a supply roll I past a device D for applying the sensitizing solution to the sound-track zone of the film. thence through a dryer 8 for drying the film and thence into a tank 9 filled with water.

' By drying the film before entering tank 9 succes 25 sive films leave tank 9 with the same degree' of moisture; if the film were not so dried successive films would enter tank 9 with different degrees of moisture and therefore leave the tank with different degrees of moisture. After entering the tank 9 the film may loop back and forth over a series of rollers I I to permit the gelatin coating to soak up a predetermined amount of moisture before contacting the matrix M. Matrix M is fed from a supply roll I2 through a dye tank I3, thence past an air-jet device A for blowing off the supercial dye, thence past a device D for applying the aforesaid mordant to the sound-trackl zone, thence past a suction device S for removing any excess of mordant which has not been absorbed by the sound-track zone, thenceV through a water tank I4 to wash the surface of the matrix and thence through the water tank 9 to the seating rolls 6. By bringing the matrix M and the film F in contact under water the danger of trapping air bubbles between the two lms is avoided. The belt I enters and leaves the tank 9 through slots provided with water traps to minimize the leakage of water through the slots.

After being seated in superposition on the belt the two films pass through an exposure box I6 containing a light source II for exposing the sound-track zone of the film F through the dyed sound-track of the matrix M. After traveling together long enough for the dye in the picture areas to transfer from the matrix M to the film F the two lrns are fed from the belt over a' roller I8 into a dry box I9 where the two films are stripped apart at 20;. the matrix M looping- 50 back and forth over rolls 2| to dry the matrix and then feeding to a take-up roll 22 and the film Fl looping back and forth over a series of rolls 23 to dry the lm and then feeding through tanks 24 and 26. Tank 24 contains the soluble' iron g5 cyanide developer for developing the sound-track and tank 28 contains water for washing away the unexposed iron salts. When the pictures on the iilm F are printedv with a single color, suchv as black, the film F may 70 be dried after leaving tank 28. However in color printing one or more additional colors may be printed on the film F after it leaves the tank 26. In a three-color process involving yellow, magentaand cyan, the first color with which the sound-l 75 track is printed, is preferably yellow. In Fig. 1

5 the nlm F is fed into another tank 29 corressponding to tank 9 Where it is again seated on the belt I and a second matrix M', after being dyed with the second color in a manner similarl to that already described in connection with the matrix M, is fed to the belt in superpositionvwith the lm F. After the last color has been. printed the two films are fed from the belt, peeledapart, dried and wound in separate rolls. Thus in a two-color process, such as illustrated in Fig. 1, the films are stripped apart and dried in a cabinet 3l and then separately wound in rolls 32 and 33. f course the film must be protected fromlight strong enough to cause a fogging exposure,` at

least until the unexposed iron salts have been washed out.

The device D, which applies the sensitizing solution to the sound-track zone of the film, comprises a pair of rollers 33, a tube 3l leading from a suitable container, a head 38 mounted on a bracket 39 for supporting the tube 3l and a camels hair brush 4I mounted in the lower end of the tube 3l for applying a stripe of the solution to the sound-track zone of the lm. As shown in Figs. 4 and 5 the sound-track zone 42 is located between the picture spaces 43 and one of the rows of sprocket holes 44. The device D for applying the mordant may be similar to the device D. The blow-off device A has an oblique slot 46 (Fig. 4) through which a sheet of air is emitted under pressure, the sheet beinginclined somewhat downwardly so as to roll back the dye which adheres to the surface of the lm. The suction device S has a tubular inlet 4l which projects into juxtaposition to the path of the soundtrack zone of the matrix and through which is drawn any mordant which has not been absorbed by the sound-track zone while the matrix travels from the mordant applicator D to the suction device.

As indicated above the ferricyanide may also be incorporated in the sound-track zonevon the lm F before the sound-track zone is exposed, and both the ferrie salts and the ferricyanide may be incorporated in the sound-track zone before the film is fed into the imbibition apparatus, in which case the tanks 24 and 2B may be omitted. In this case there is no reaction between the iron salts and ferricyanide in tank 9 because the ferrie salts have not yet been converted into ferrous Salts. When the sound-track zone .is exposed in the box I6 the reaction begins because the sound-track zone has already absorbed some moisture in the tank 9. When the film F reaches tank 29 the reaction is completed and the film is washed. Instead of eliminating both tanks 24 and 2t, tank 26 may be retainedv to develop the sound-track and thoroughly wash the film, so that the water in tank 28 is not contaminated by the iron salts, the ferrcyanide or the reaction products of the two.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. In the art of printing pictures by imbibition, from a dyed matrix having both pictures an a sound-track, on a water absorptive film having soluble light-sensitive ferric salts in its soundtrack zone, the method which comprises dyeing the matrix with an acid dye, continuously feeding the iilm and matrix into face-to-face contact and thence conducting the lm and matrix along predetermined'paths withthe film and matrix in face-to-face contact along a common portion of the paths to permit dye to be imbibed by the film from the matrix, in said common portion printing the sound-track in said zone with light passing through the matrix to convert the ferrie salts into ferrous salts, and farther along the path of the film developing the sound-track with soluble iron cyanide developer selected from the class consisting of ferricyanide and ferrocyanide salts `to produce a sound-track in the form of a light-absorptive, insoluble, iron cyanide, washing the nlm to remove the unexposed iron salts, and after the matrix is dyed and before it reaches the nlm 4mordanting the sound-track zone of the matrix with a basic dye to prevent dye transfer from matrix to nlm in said zone, whereby the migration of ferrie salts from the lm to the matrix does not affect the quantity of dye in the sound-track zone of the matrix throughout successive printings.

2. In the art of printing pictures by imbbition, from a dyed matrix having both pictures and a sound-track, on a water absorptive film having soluble light-sensitive ferrie salts in its soundtrack zone, the method which comprises dyeing the matrix with an acid dye, continuously feeding the film and matrix into face-to-face contact and thence conducting the lm and matrix along predetermined paths with the film and matrix in face-to-face contact along a common portion of the paths to permit dye to be imbibed by the film from the matrix, in said common portion printing the sound-track in said Zone with light passing through the matrix to convert the ferrie salts into ferrous salts, and farther along the path of the lm developing the ferrous salts with ferricyanide to produce a sound-track in the form of a light-absorptive, insoluble, iron cyanide, washing the lm to remove the unex-.- posed iron salts, and after the matrix is dyed and before it reaches the film mordanting the soundtrack zone of the matrix with a basic dye to prevent dye transfer from matrix to film in said zone, whereby the migration of ferrie salts from the film to the matrix does not affect the quantity of dye in the sound-track zone of the matrix throughout successive printings.

3. In the art of printing pictures by imbibition, from a dyed matrix having both pictures and a sound-track on a water absorptive film having in its sound-track zone soluble light-sensitive ferrie salts and ferricyanide, the method which comprises dyeing the matrix with an acid dye, continuously feeding the film and matrix into face-toface contact and thence conducting the nlm and matrix along predetermined paths with the film and matrix in face-to-face contact along a common portion of the paths to permit dye to vbe imbibed by the film from the matrix, in said common portion printing the sound-track in said zone with light passing through the matrix to convert the ferrie salts into ferrous salts, and farther along the path of the lm passing the film through a water bath to cause said ferricyanide to develop the sound-track in the form of a lightabsorptive, insoluble, iron cyanide, washing the lm to remove the unexposed iron salts, and after the matrix is dyed and before it reaches the film mordanting the sound-track zone of the matrix with a basic dye to prevent dye transfer from matrix to lm in said zone, whereby the migration of ferrie salts from the film to the matrix does not affect the quantity of dye in the soundtrack zone of the matrix throughout successive prntings.

WADSWOR'JSH EQPOHL.'

REFERENCES lCITED The following references are of record in the le of this patent:

UNITED STATES PATENTS lNumber Name Date Thornton Feb. 28, 1922 Hernandez-Mejia Nov. 24, 1925 Tuttle June 2, 1931 Tuttle Mar. 7, 1933 Capstaff Sept. 11, 1934 NumberA i1 2,009,689

Number Great Britain Aug. `30, 1940 

